The integrated biodiversity survey compared a
range of land-use practices in the Bungo-Tebo district in the lowland peneplain
of Jambi. The landscape consists of an undulating plain, formed as marine
sediment in the tertiary period (Van Noordwijk et al., 1995, 1997b). Most of the land in the interfluves is
covered by highly leached oxisols/ultisols, with more recent sediment and
generally higher fertility near the rivers where inceptisols and entisols
dominate. The survey was intended to highlight the effects of land use on
biodiversity, so variation in soil types would be minimized in the selection of
sample points. As older human settlements, and hence an important land use type
in the form of extensive rubber agroforest, are usually found close to the
streams and rivers, not all sampling points could be located in the
oxisol/ultisol complex.

Data on conservative soil
properties such as texture, pH and exchangeable cations were collected to check
the extent to which all variation in biodiversity can be attributed to land use
and management, rather than to a priori
differences in soil and vegetation. Soil organic matter content and bulk
density are likely to be influenced by land use, and may themselves become
factors influencing development of vegetation and ecosystem function.The above-ground biodiversity sampling
protocol (Gillison et al., this
volume) includes an estimate of woody plant basal area. For the full
characterization of terrestrial carbon stocks the ASB project has developed a
protocol quantifying biomass in trees, understorey vegetation, surface litter
and dead wood, and soil carbon in the top 30 cm of the profile. Data were
collected with this protocol to help calibrate the simpler assessment of woody
plant basal area.

Decline of soil organic carbon content of (former) forest soils after
forest conversion is a major concern, both for the on-site fertility of such
soils and for estimating the impacts of land-use change on the global C balance
in the context of climate change. Effects of land-use change on soil organic
carbon (Corg), may be difficult to quantify from limited datasets,
as generally no historical data are available of Corg before forest
conversion, and one normally has to rely on 'paired' datasets of sites still
under forest and those now under other land uses. Even moderate differences in
soil texture and/or pH, however, can lead to changes in Corg of
similar magnitude as those of the land use change. Van Noordwijk et al. (1999) proposed to use a ratio of
the measured Corg and a reference Corg value for forest
(top) soils of the same texture and pH as a 'sustainability indicator'. A
substantial dataset of soils on Sumatra (Indonesia)
was used to derive a pedotransfer function for such a reference value (Van
Noordwijk et al., 1997a).

10.2.Methods:

Methods for quantifying carbon stocks were used as specified in the ASB
protocol (Palm et al., 1994). For the
vegetation and soil macrofauna, the sampling area was based on the 40 x 5 m2
transect, as before. All tree diameters above 5 cm in the forest plots were
measured by the BIOTROP team and data were converted into aboveground biomass
with an allometric equation modified from Brown (1997) on the basis of
additional data collected in the Jambi area (Ketterings et al., in prep.):

Y (kg tree-1) = 0.092 Diam 2.60

where tree diameter (Diam) is measured in cm.

Understorey and herbaceous layer vegetation was measured in eight0.25 m2 quadrat samples (or four
1-m2 samples for non-forest plots); total fresh weight was measured,
and subsamples were collected for determining dry matter content. Diameter and
length of dead wood (> 5 cm diameter) were measured within the 40 x 5 m2
transect and converted to volume on the basis of a cylindrical form; three
apparent density classes were used and ring samples were taken to assess the
dry weight bulk density (g cm-3) of the partly decayed wood .
Surface litter (including wood < 5 cm diameter) was collected down to the
surface of the mineral soil in eight 0.25 m2 samples. To remove
mineral soil particles, the litter samples were washed and sundried; subsamples
were taken for dry matter content.

Soil bulk density was measured for the 0-5 cm top soil
layer (8 replicates per sampling point) by carefully inserting a 165 cm3
ring from the mineral soil surface, just below the litter layer.

Soil samples were collected (composited from 8 sample
points per 200 m2 sampling area) for the 0-5, 5-10, 10-20, 20-30 cm
depth zone below the litter layer, passed through a 2 mm sieve and air-dried
for analysis of texture (sand, silt, clay), pH (1N KCl), pH(H2O), P BrayII,
Corg (Walkey and Black), Ntot (Kjeldahl), exchangeable K,
Ca, Mg, Na, Al and H, and effective cation exchange capacity (ECEC) by
summation. All these routine soil measurements were done on air-dried, sieved
soil in the soils laboratory of BrawijayaUniversity
(Malang, Indonesia)
with methods consistent with those described in Anderson and Ingram (1993). In
addition, a size-density fractionation of macro-organic matter based on Ludox
solutions of various densities was used, as described by Hairiah et al. (1995, 1996a) and Meijboom et al. (1995), for the 0-5 and 5-10 cm
depth zone. The reference value for Corg(‘Cref’) was calculated on the basis of soil
texture on the basis of a large data set of Sumatran soils (Van Noordwijk et al. 1997a, 1998, 1999).

10.3.Field notes on sampling points:

Primary forest (BS 1,2) - two samples behind the permanent
forest plots of BIOTROP but in the 25 ha reserve; the plots are on two sides of
a small stream. Logged-over forest (BS 3,4,5) - three samples: no. 3 close to
the second primary forest plot, on a ridge with logging track overgrown by
ferns, secondary forest regrowth and patches of undisturbed forest; no. 4 and 5
in the logged-over forest (1983) where BIOTROP has permanent plots; no. 4
includes a recent tree fall, no. 5 appears to be little affected by the
logging. Industrial timber plantation(HTI) (BS 6,7)- 5-year old Paraserianthes falcataria plantation;
no. 6 close to the road and forest edge, no. 7 in the centre of the HTI area;
(the Paraserianthes still seemed to
be affected by a moth). Rubber plantation (BS 8,9) - 8-year
old intensively managed rubber established by slash-and-burn from logged-over
forest, along the main logging road in Pasir Mayang; both plots are part of a
18 ha farm established by a former employee of PT IFA, and currently partly
operated by share-tappers; the plantation was established from seedlings obtained
from the plantation project across the river (GT1 ?) and was managed in
plantation-style (but without legume cover crops). Jungle rubber (BS 10,11)
- a 45 (?) year old rubber agroforest in Dusun Tuo (across the Batang Hari
river from Pasir Mayang), in a landscape with a lot of newly planted rubber
(mostly seedlings). Imperata grassland (BS 12,13) - in Kuamang Kuning, close to the
Imperata plots sampled in 1996.
Cassava (BS 14,15) - in Kuamang Kuning, close to Imperata plots; part of the fields was opened by tractor,
apparently for planting oil palm. Chromolaena fallow (BS 16) - in
Dusun Tuo, close to the jungle rubber (10 and 11); a 3 (?) year old fallow,
about to be re-opened for planting rice.

10.4.Results and Discussion:

Soil characteristics are summarized in Table
10.1. Soil texture data show that the sampling points belong to essentially
three groups:

soils
with less than 20% clay in the top 5 cm (sampling points BS 1, 2 ,4, 5 and 6),

soils
with more than 40% clay in the top 5 cm (sampling points BS8 and 9).

These differences are probably a priori and not caused by current land
use. The location of the rubber plantation (8&9) on a soil of higher clay
content is probably typical for the position of rubber in the landscape.
Comparisons between sites in different classes have to take these soil
differences into account.

All sites were acid, with the
highest pH (H2O) values found in the Imperata and Cassava sites around the transmigration village,
possibly indicative of past lime applications (note that pH(KCl) values show
less variation) and the Chromolaena
fallow plot.

Soil organic carbon (Corg)
and total N (Ntot) showed a strong decrease with depth, justifying
the separation of the 0-5 and 5-10 cm depth layer. Available soil phosphorus
levels were very low in sample 8, and relatively high in 10 and 11. The
effective cation exchange capacity was low (< 12 cmole kg-1)
in all soils. Al saturation was high in all soils, but lowest in sites 12 and
13. Overall, a weak buyt statistically significant relationship was found
between Al-saturation and pH(H20):

Al-sat = 104.0 – 12.5 * pH(H2O)[n
= 63, r2 = 0.23, P < 0.001]

Al-sat = 99.2 – 14.8 * pH(KCl[n
= 63, r2 = 0.05, P = 0.045]

Bulk density measurements (Table 10.2) showed substantial
differences between the plots; tracks in the logged over forest, the young
industrial timber plantation and the Cassava and Imperata plots had a bulk density substantially higher than that of
natural forest; the logged over forests outside the skidding track had a high
coefficient of variation in bulk density, indicating patch-wise soil compaction

The differences between Corg
of the topsoil between the sampling points probably reflect differences in soil
texture as well as land use. When the Corg/Cref ratio is
compared, the data appear to reflect land use effects more clearly (compare
Figure 10.1A and 10.1C). The size/density fractionation data (Figure 10.1C)
failed to differentiate clearly between the land uses.

Table 10.1.Measured soil parameters

No.

LUT

Depth

Texture

pH_H2O

pH_KCl

C_org

N_tot

C/N ratio

P_brayII

Exchangeable cations

ECEC

Al_sat

Sand

Silt

Clay

K

Na

Ca

Mg

Al

H

cm

%

%

%

mg kg-1

cmole kg-1

%

1

NF

0_5

62

24

14

4.0

3.5

4.01

0.28

14.3

10.2

0.16

0.34

1.65

0.41

4.19

1.16

7.91

53.0

1

NF

5_10

62

20

18

4.7

3.8

1.86

0.14

13.3

4.19

0.09

0.24

1.54

0.51

4.19

0.85

7.42

56.5

1

NF

10_20

62

20

18

4.9

3.9

1.20

0.09

13.3

2.09

0.08

0.22

1.54

0.10

3.59

0.89

6.42

55.9

1

NF

20_30

64

18

18

4.9

4.0

0.80

0.06

13.3

1.69

0.06

0.22

1.03

0.07

3.53

0.83

5.74

61.5

2

NF

0_5

67

22

11

4.2

3.5

3.21

0.19

16.9

9.19

0.19

0.31

1.54

0.62

3.71

1.27

7.64

48.6

2

NF

5_10

69

19

12

4.7

3.8

2.01

0.13

15.5

6.69

0.11

0.24

1.54

0.10

3.53

0.83

6.35

55.6

2

NF

10_20

66

17

17

4.8

3.7

1.61

0.12

13.4

2.69

0.11

0.23

3.61

1.03

3.17

0.93

9.08

34.9

2

NF

20_30

67

17

16

4.8

4.0

0.96

0.07

13.7

1.69

0.09

0.20

1.54

0.1

2.99

1.06

5.98

50.0

3

LOF

0_5

54

8

38

4.5

3.7

1.85

0.13

14.2

2.69

0.12

0.25

1.55

0.51

2.93

0.8

6.16

47.6

3

LOF

5_10

81

10

9

5.2

3.8

1.53

0.12

12.8

5.19

0.10

0.29

2.06

0.21

2.69

0.24

5.59

48.1

3

LOF

10_20

67

13

20

5.0

4.0

1.36

0.11

12.4

4.69

0.08

0.20

1.03

0.51

2.69

0.74

5.25

51.2

3

LOF

20_30

65

13

22

4.8

4.0

1.20

0.08

15.0

3.16

0.06

0.18

1.02

0.51

3.02

0.99

5.78

52.2

4

LOF

0_5

81

11

8

4.5

3.6

4.66

0.28

16.6

18.0

0.15

0.25

1.12

1.02

4.15

1.09

7.78

53.3

4

LOF

5_10

79

10

11

4.0

3.5

3.13

0.18

17.4

5.19

0.11

0.25

1.55

1.34

3.29

1.38

7.92

41.5

4

LOF

10_20

77

10

13

4.6

3.7

2.09

0.12

17.4

3.69

0.09

0.25

2.57

0.41

3.29

1.38

7.99

41.2

4

LOF

20_30

74

10

16

4.7

3.7

1.85

0.12

15.4

2.69

0.08

0.28

2.37

0.21

3.41

0.95

7.30

46.7

5

LOF

0_5

79

13

8

4.2

3.3

4.41

0.28

15.8

6.19

0.20

0.39

2.06

0.31

2.69

1.65

7.30

36.8

5

LOF

5_10

79

13

8

4.5

3.8

1.91

0.12

15.9

6.13

0.10

0.28

1.12

1.22

2.97

0.97

6.66

44.6

5

LOF

10_20

76

11

13

4.8

3.9

1.61

0.10

16.1

4.65

0.07

0.22

1.33

0.41

2.97

0.73

5.73

51.8

5

LOF

20_30

75

15

10

4.8

4.0

1.27

0.10

12.7

4.15

0.07

0.16

1.22

0.61

2.67

0.66

5.39

49.5

6

HTI

0_5

84

8

8

4.4

3.9

2.78

0.17

16.4

18.5

0.18

0.38

2.04

0.61

2.61

0.47

6.29

41.5

6

HTI

5_10

82

10

8

4.3

3.9

2.15

0.13

16.5

9.10

0.06

0.19

1.33

1.22

2.67

0.72

6.19

43.1

6

HTI

10_20

79

8

13

4.8

4.0

1.67

0.10

16.7

5.64

0.06

0.14

1.54

1.02

2.31

0.77

5.84

39.6

6

HTI

20_30

74

10

16

4.8

4.1

0.50

0.05

10.0

2.66

0.04

0.13

1.22

0.31

2.55

0.60

4.85

52.6

Table 10.1.Measured soil parameters

No.

LUT

Depth

Texture

pH_H2O

pH_KCl

C_org

N_tot

C/N ratio

P_brayII

Exchangeable cations

Al sat

Sand

Silt

Clay

K

Na

Ca

Mg

Al

H

ECEC

cm

%

%

%

mg kg-1

cmole kg-1

%

7

HTI

0_5

46

28

26

5.2

3.8

4.21

0.28

15.0

8.78

0.41

0.62

4.68

1.56

1.33

0.87

9.47

14.0

7

HTI

5_10

45

19

36

5.2

3.9

2.11

0.16

13.2

1.20

0.21

0.45

4.16

1.14

1.89

0.21

8.06

23.4

7

HTI

10_20

43

22

35

4.8

3.6

1.78

0.14

12.7

0.69

0.19

0.43

3.12

1.04

4.23

0.80

9.81

43.1

7

HTI

20_30

43

22

35

4.8

3.6

1.62

0.11

14.7

0.19

0.12

0.38

1.87

1.25

5.14

0.90

9.66

53.2

8

RUB_P

0_5

14

27

59

4.6

3.5

5.97

0.38

15.7

1.20

0.19

0.36

2.41

0.95

3.96

2.07

9.94

39.8

8

RUB_P

5_10

14

11

75

4.5

3.7

2.95

0.18

16.4

0.19

0.12

0.29

2.10

0.31

2.81

1.25

6.88

40.8

8

RUB_P

10_20

12

16

72

4.9

3.7

1.96

0.13

15.1

0.19

0.12

0.33

1.68

0.41

2.81

0.86

6.21

45.2

8

RUB_P

20_30

11

13

76

4.9

3.8

1.86

0.12

15.5

0.19

0.1

0.32

1.52

0.94

1.63

0.71

5.22

31.2

9

RUB_P

0_5

15

41

44

4.4

3.6

3.27

0.53

6.2

10.0

0.27

0.38

1.78

0.59

5.67

1.89

9.40

60.3

9

RUB_P

5_10

13

15

72

4.8

3.7

2.41

0.31

7.8

7.50

0.13

0.36

1.62

0.42

3.23

1.21

7.65

42.2

9

RUB_P

10_20

13

18

69

4.7

3.9

2.19

0.16

13.7

1.25

0.09

0.18

1.80

1.08

3.14

1.04

7.50

41.9

9

RUB_P

20_30

12

23

65

4.5

3.9

2.13

0.14

15.2

0.18

0.05

0.17

1.57

0.63

3.36

1.08

6.82

49.3

10

J_RUB

0_5

6

70

24

5.2

3.8

6.23

0.46

13.5

41.5

0.51

0.69

2.37

0.76

5.31

2.63

10.7

49.5

10

J_RUB

5_10

7

58

35

5.1

3.8

3.97

0.28

14.2

17.2

0.23

0.63

2.12

0.42

5.05

1.49

11.1

45.6

10

J_RUB

10_20

5

54

41

5.1

3.8

2.81

0.22

12.8

10.5

0.22

0.37

1.59

0.21

4.93

1.48

8.81

56.0

10

J_RUB

20_30

5

46

49

5.1

3.8

2.13

0.19

11.2

4.78

0.13

0.31

1.26

0.31

4.88

1.15

8.37

58.3

11

J_RUB

0_5

9

52

39

5.4

3.9

5.76

0.37

15.6

32.8

0.46

0.68

2.46

0.33

3.39

1.76

8.47

40.0

11

J_RUB

5_10

9

50

41

5.3

3.9

3.20

0.27

11.9

10.2

0.25

0.45

1.71

0.23

3.98

1.53

8.38

47.5

11

J_RUB

10_20

9

42

49

5.2

3.8

2.44

0.23

10.6

5.44

0.25

0.42

1.84

0.32

3.77

1.26

8.13

46.4

11

J_RUB

20_30

7

33

60

5.1

3.8

2.11

0.20

10.6

1.30

0.27

0.52

1.72

0.34

3.10

1.02

7.21

43.0

12

IMP

0_5

66

14

20

5.8

4.1

2.19

0.13

16.8

8.27

0.20

0.36

1.56

1.04

1.21

0.05

5.39

22.4

12

IMP

5_10

67

11

22

5.5

4.2

2.03

0.12

16.9

6.25

0.12

0.37

1.35

0.41

1.03

0.61

3.33

30.9

12

IMP

10_20

69

9

22

5.3

3.8

1.78

0.10

17.8

1.20

0.11

0.31

1.35

0.73

1.51

0.31

4.62

32.7

12

IMP

20_30

61

13

26

5.2

3.9

1.22

0.09

13.6

1.20

0.05

0.22

1.56

0.52

2.00

0.39

4.66

42.9

13

IMP

0_5

66

13

21

5.7

4.0

2.23

0.13

17.2

4.15

0.09

0.42

1.12

0.51

1.18

0.67

3.71

31.8

13

IMP

5_10

67

5

28

5.6

4.0

2.10

0.12

17.5

3.16

0.20

0.45

1.12

0.71

1.48

0.68

4.63

32.0

Table 10.1.Measured soil parameters

No.

LUT

Depth

Texture

pH_H2O

pH_KCl

C_org

N_tot

C/N ratio

P_brayII

Exchangeable cations

Al sat

Sand

Silt

Clay

K

Na

Ca

Mg

Al

H

ECEC

cm

%

%

%

mg kg-1

cmole kg-1

%

13

IMP

10_20

65

8

27

5.4

4.0

2.07

0.12

17.3

2.66

0.18

0.44

1.72

0.41

1.78

0.19

5.21

34.2

13

IMP

20_30

65

8

27

5.4

4.0

1.51

0.09

16.8

1.67

0.14

0.41

1.34

1.02

1.78

0.38

4.88

36.5

14

CAS

0_5

61

16

23

5.0

3.8

1.51

0.11

13.7

18.0

0.11

0.25

1.02

0.81

2.19

0.09

4.76

46.0

14

CAS

5_10

57

16

27

5.0

3.8

1.27

0.10

12.7

6.13

0.10

0.24

1.63

0.94

2.07

0.82

5.07

40.8

14

CAS

10_20

54

19

27

5.0

3.8

0.97

0.09

10.8

2.21

0.06

0.23

2.29

0.63

2.12

0.71

6.15

34.5

14

CAS

20_30

51

16

33

4.8

3.8

0.49

0.05

9.8

0.19

0.05

0.22

1.56

1.04

2.48

0.41

6.06

40.9

15

CAS

0_5

68

13

19

5.1

3.9

1.78

0.12

14.8

17.4

0.11

0.36

2.08

0.45

1.51

0.50

4.92

30.7

15

CAS

5_10

61

18

21

5.1

3.8

1.70

0.11

15.5

7.77

0.11

0.34

1.56

0.52

1.51

0.69

4.54

33.3

15

CAS

10_20

60

16

24

5.2

3.9

1.62

0.10

16.2

6.76

0.11

0.31

1.56

1.04

1.81

0.70

5.52

32.8

15

CAS

20_30

60

16

24

5.2

3.9

1.38

0.10

13.8

4.23

0.08

0.29

1.56

0.41

1.81

0.70

4.85

37.3

16

CHRO

0_5

9

66

25

5.7

4.2

4.66

0.32

14.6

35.1

0.48

0.88

2.64

2.41

1.20

0.88

8.31

14.4

16

CHRO

5_10

9

59

32

5.3

3.9

3.64

0.28

13.0

17.9

0.28

0.71

2.28

0.57

2.65

1.49

7.37

36.0

16

CHRO

10_20

6

57

37

4.9

3.8

2.72

0.20

13.6

6.49

0.27

0.61

2.96

0.22

2.85

1.43

8.40

33.9

16

CHRO

20_30

10

52

38

4.8

3.7

2.27

0.16

14.2

3.37

0.12

0.54

1.62

0.54

3.45

1.12

7.70

44.8

Table 10.2.

Bulk density (g cm-3) of the top 5 cm based on 8 replicates
per sampling point

Number

Code

Mean

Standard

deviation

Coefficient

of variation

Standard error

of mean

BS01

NF

0.67

0.164

0.245

0.06

BS02

NF

0.69

0.141

0.203

0.05

BS03

LOF

0.87

0.377

0.434

0.13

BS04

LOF

0.75

0.155

0.206

0.05

BS05

L0F

0.69

0.268

0.386

0.09

BS05

TRACK

1.20

0.218

0.181

0.08

BS06

HTI

1.01

0.155

0.154

0.05

BS07

HTI

1.00

0.108

0.107

0.04

BS08

RUB_P

0.79

0.069

0.088

0.02

BS09

RUB_P

0.66

0.138

0.208

0.05

BS10

J_RUB

0.65

0.063

0.097

0.02

BS11

J_RUB

0.73

0.103

0.141

0.04

BS12

IMP

1.12

0.076

0.068

0.03

BS13

IMP

1.26

0.089

0.071

0.03

BS14

CAS

1.31

0.142

0.108

0.05

BS15

CAS

1.16

0.146

0.126

0.05

BS16

CHROM

0.77

0.079

0.103

0.03

Table 10.3.

Soil organic matter data compared to the
reference value Cref

(based on regression of Corg on
soil texture fore a large data set of Sumatran soils)

Table 10.4
summarizes data on the above and belowground carbon stocks for all sampling
points. The total values for the forest plots (around 50 kg m-2,
corresponding to 500 Mg ha-1) are consistent with other data for
lowland forests sampled in the ASB project (Woomer et al., 1998?). The logged over forests had substantially lower
biomass AC stocks, but partly made up fror the difference by high dead wood
(necromass) stocks.

Figure 10.2. Relation
between total aboveground C stock (biomass and necromass) and time since last
slash, burn or cultivation event; the slope indicates an average annual Cstock increment of 2.5 Mg C ha-1
year-1